Tungsten-rhenium-tantalum alloys



w Jig" United States Patent 3 160 50-1 rUNosrEN-nnENrUa rhANTALUM ALLOYS Lee S. Richardson, Monroeviile, Pa, Allen I. Lewis, de-

ceased, late of Forest Hills, Pa, by Bernard .1. Am-

brose, administrator, Monroevilie, and Leonard L.

France, Mount Lebanon, Pa, assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Sept. 15, 1961, Ser. No. 138,531 3 Claims. (Q1. 75-176) The present invention relates to tungsten base alloys suitable for use where high strength at elevated temperatures and low temperature ductility is required.

Fabricable alloys possessing a relatively low ductile to brittle transition temperature and having a high strength at extremely high temperatures have many industrial and military applications, and it is generally recognized that future developments in many fields are closely tied to the availability of new and improved alloys possessing these properties. For example, the development of improved rocket nozzles and blades for gas turbines is dependent upon the availability of such alloys. Also, the alloys should prove to be very valuable for lamp and tube applications.

In accordance with this invention it has been found that workable alloys possessing high strength at temperatures above 2000 F. can be produced by alloying tungsten, tantalum and rhenium in certain proportions.

Therefore, the object of this invention is to provide workable alloys which possess a relatively good ductility both at room temperature and at sub-zero temperatures and which possess high strength at elevated temperatures, comprising predetermined proportions of tantalum, and rhenium, the balance, over 50% by weight being tungsten with small amounts of incidental impurities.

Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.

The single figure is a graph setting forth the hardness of tungsten-tantalum-rhenium alloys as a function of temperature.

In accordance with the present invention ternary tungsten base alloys have been produced comprising from 1 to by weight of rhenium, from 1 to 10% by weight tantalum, and the balance being tungsten, with small amounts of incidental impurities. The alloys are characterized by high mechanical strength at elevated temperatures, low temperature ductility and the ability to be easily wrought to shape by hot or Warm working. In a preferred embodiment, the alloys of this invention comprise from 2 to 8% by weight rhenium, from 2 to 8% by Weight tantalum, and the balance being tungsten, with small amounts of incidental impurities.

The alloy may be melted by a one of several procedures which will insure homogeneity and a minimum of contamination. For example, unalloyed, high purity, tungsten together with proper amounts of pure tantalum and rhenium in powder form may be pressed into a bar or electrode and may be consumably arc melted preferably in a vacuum, though an inert gas atmosphere of argon, may be employed. The resulting ingot may be vacuum remelted several times to achieve homogeneity, then the resulting ingot may be hot worked to the desired shape; The alloy may also be prepared by levitation melting of a ball or rod of the alloy, using induction heating and levitating coils. Electron beam melting and non-consumable arc melting of the alloys is also satisfactory.

The following example is illustrative of the present invention. A group of alloys comprising tungsten, tantalum and rhenium within the limits set forth herein were prepared by non-consumable arc melting in a vacuum of an absolute pressure of below 25 microns. Samples of the resulting ingots were tested for hardness at dilierent temperatures ranging from 240 F. to 2000 F. The results of these tests are indicated in Table I wherein percentages given for the compositions are by weight and the hardness values are diamond pyramid hardness (DPH).

The alloys described herein may be hot worked or wrought to shape and, in some instances they may be cold worked. 7

Referring to the figure, there is shown a graphical comparison of two of the alloys selected from Table I with pure tungsten and a binary alloy of tungsten and rhenium. It may be concluded therefrom that the addition of tantalum and rhenium to tungsten increases the hardness at elevated temperatures and causes an increase in mechanical strength thereby. On the other hand, at room temperature and below the hardness of the tungsten alloy decreases with increasing amounts of the alloying components thereby indicating a greater ductility than pure tungsten at these temperatures.

It will be understood that the above description is only exemplary and not in limitation of the invention.

We claim as our invention:

1. A tungsten base alloy consisting essentially of, by weight, 1 to 10% rhenium, 1 to 10% tantalum and the balance tungsten.

2. A tungsten base alloy consisting essentially of by weight, 2 to 8% rhenium, 2to 8% tantalum and the balance tungsten.

3. A tungsten base alloy consisting essentially of by weight, 8% rhenium, 4% tantalum and the balance tungsten.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES H. Braun et al.: Contribution to the Technology of the Tantalum-Tungsten Alloys, TF-5528, pages 2 and 10. (Reprint of: Plansee Proceedings, 1958, High-Melting Metals, pp. 264-276, Pergamon Press, 1959.)

Patented Dec. 8, 1964 

1. A TUNGSTEN BASE ALLOY CONSISTING ESSENTIALLY OF, BY WEIGHT, 1 TO 10% REHNIUM, 1 TO 10% TANTALUM AND THE BALANCE TUNGSTEN. 